Rotary engine



Nov. 17, 1931. L. M. WOLF 1,332,579

ROTARY ENGINE Filed Dec. 1, 1928 2 Sheets-Sheet 2 14 465 may/11471111111111! ll QQ;

patented Nov. 17, 193 11 nrursnlsrarss earner tFF -FICE LESLIE? MILTON WOLF, OF LOS ANGEIJES, CALIFORNIA ROTARY ENGINE Application fildllecember 1, 1928. Serial No. 322,985.

object, of the invention is to provide improvements-in an engine of. the type comprising a rotor revolving in a piston chamber,andprovidedwith sliding piston members cooperating With the body of therotor and the Walls of the pistonchamber toprovide working chambersvarying in. volume as the rotative movement of the rotor proceeds, and in which a Working tluid may be expandedand give out energy to the rotor,

or may becompressed by energy absorbed from-the rotor.

The invention Was primarily devised for use in rotary. internal combustion orv explosion engines, and in such use each working -.;0 chambenformed by the rotor,,an adjacent pair of sliding piston members and the piston chamber ivalls serves as an explosion chamber inwhich liquid or gaseous fuel may be ignited and burned after an initialcomiressionof the. fuel and air charge in said working chamber. The invention is characterized by certain novel characteristics particularly adapted for use in an explosion engineof the so-called Diesel type, or analogous types in which the fuel and air charge iscompressed to a relatively high pressure before ignition. Features of my invention may be used, however, in prime movers driven by steam or compressed air, as .WGll as by gaseous products of combustiomand may also be used in gas compressors, and certain novel characteristics or features, of the invention are also adapted for use in high speed rotary liquid pumps.

in the character of theapparatus, or inits general'torm except in respect tothe means for supplying-fluid to, and dischargingfluid i'rom,the apparatus.

My improved engine is-characterized in particular by the special undulatory; t'o'rm.

given to opposing sidewalls of the piston chambenand contributing to operationat In general, the difierent-uses suggested require no changeton, rotor and piston chamber. Walls and with a relatively small amount of friction and Wear.

The invention is further characterized by special features 01": construction and arrangementv of parts provided for efiectively sealing the joints between the relatively movable piston, rotor and piston Wall parts.

The invention isfurther characterized by features of construction and arrangement contributing to. the production of a rotor of relatively sr' all Weight butiot' ample strength and rigidity, and also by provisionsmade for. coolingthe pistons; and rotorbody, such provisions being. of. especial.v importance When the. invention isincorporated in. an explosion or internal combustion engine.

The various teaturesot: novelty. which characterize my invention are pointed out with particularity in the claims .annexedlto and forming a part of this specification] For a better understanding oft'he invention, however, and the advantages possessed by it reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodimentiof myinvention.

Of the drawings: y i

Fig. 1 is anelevationwith portions of the engine broken awayand in section,

Fig. iZis a developed circumferential section on the line 2.-2 of Fig. 1;

3 is an elevation taken at right angles to *ig.v lwith the upper portion in section :on th line 33 of Fig. 1;

Fig. l is. a partial section on the linei l4r 1\ character; to Fig. 2 illustrating, port artable toruse in a compressor; is a view-similar to Fig.-.6 illustratin-"a port arrangement suitable for-use in a turbine; and

View similar to Fig. Gillustrating a po t arrangement suitablefor use in a liquid pump. V

' In the drawings I haveillustrated an emboalmentoi' my invention, especially devised and adapted for use as a rotary explosion or internal combustion engine. The engine shown in the drawings comprises a stationary stator casing or housing forms with bearings A. for the rotor shaft G and wi h an annular piston chamber B encircling the shalt Q. he opposite side walls B and B of the clmmber are undulatory each comprising 2. series of alternating suitably curved concave and convex portions. The convex portions of one of the side walls are in reg ter with the concave portions of the opposing side u: so that these two walls could s moved 2 y to her, they would nest or faces except who e the walls are locally moditied in term to I 'ovide the piston chamber inlet and exhaust port contact at points in their adjacent sur- .s B and .8, respectively. ln practi'e, the stator housing or casii may advantageously be formed of two similar parts meeting at the central plane of the piston chamber and secured together by suitable clamping bolts A. As shown, the two halves oi? the casing body proper are Pin mounted on and connected to a cradle or base n'icmber formed with a seat engaged through which the rotor body extends into the piston chamber.

The rotor body D may be described as a disc or cyl'ndcrdike body which is mounted on the shaft (1, and which is chan'ibered or cut away to provide cooling spaces or assages through which air is caused to flow as hereinafter described, and to provide slots or guideways D" extending into the rotor from periphery and receiving axiall movable piston vane members E which extend bctneen the opposite side walls l3 and oi the piston chamber, and between the inner and outer walls B and B of that chamber. As shown, the rotor body is formed of parts I), D and D The parts D and D which may be counterparts of one another, are arranged at opposite sides of the central member D which is in the form of a disc of metal plate. The parts l), 13* and D are keyed on the rotor shaft C. and are also secured together by clamping bolts D Each iston vane pocket or slot D e tends axia Ty through the parts D, D and D Between each pair of piston vane pockets D the member D is recessed to form a COI'IQSPOIlCllllg a r chamber or passa e d,

member D is recessed to form a simiand toe lar air space or passage (Z The webbed member D is cut away to provide restricted ports D and D providing more or less restricted communication between each space or pocket cl to the adjacent space or pocl-ret In the construction shown, air is forced into each chamber cl, and into each piston cham ber D by the centrifugal tan ellect of curved spoke-like portions D of the rotor part D which draw atmospheric air into the rotor through a :ially extending ports ih' in the housing structure. Similar spoke-like portions of the rotor port D assist in drawing air ut of the chambers and D and di charging into the atmosphere through ports A at the opposite side of the stator housing from the ports A. As shown, the parts D and D may be counter-parts, the spokelilce portions i) being so curved that vith the intended direction of rotation shown by the arrows in Figs. 1 and 2, the SPOliOS oi the member D will tend to move the air outward from the axis of the stator, whereas the spokes D of the part D will lend to draw air inward toward the stator axis.

At their outer end. the spokes or arms are integrally united with heavy annular rib parts l) of the rotor body. 'ihese rib parts extend into the slot between the stator edge portions .8 To minimize leakage, each rib D and adjacent stator edge 15' have circumfcrentially extending tongue and groove surfaces ground or otherwise suitably macliined to insure a close lit. 'ihe ribs D close short portions of the inner edge of each piston vanes slide way D.

To facilitate high speed operation, for which the invention was primarily devised, the sliding piston members 15 are advantageously made of strong light-weight material, for example, duralumin, and are advantageously made of two separate plate-like parts E and I) connected by rivets E" and spaced apart by lugs 15* carried by the plate In and through which the rivets ll extcnl. To minimize leakage through the 10.1 ietween the piston chamber walls B, i l) and l3, and the rotor and piston parts, suitable joint sealing provisions are required. its shown, these provisions comprise an L-shaped memher G and a U-shaped member H at each end, being located between the plates la and E 'lo force the various members G and axially into contact with the adjacent side walls 13 and B and to force the base member of each arm G into engagement with the corresponding wall portion 13, 1 provide a spring 1 and a linked structure comprising lever elemei s J and J. lhe spring 1, to permit it to ti between the narrow space l3Gil'\ ten the plates E and E is advantageously formed of a reversely bent strip or bar of metal. lit acts between a lug E carried by the plate E adjacent its outer edge, and the linked. structi re, and tends to expand the latter in the axial diarena-ere *rection and thereby causeo'nezarmdateach end of the linked-structure to bear axially outward and radially inward againstthe cor- A second arm J at each end of the and J adjacent the same side of the piston chamber are pivotally connected, and the two arms J are pivotally connected at their-inner ends, and the two arms Jare also pivotally connected at their inner ends.

In operation, the radially extending portionsot each of the members G and H tend to preventleakage between the corresponding end-otthe corresponding piston member E,

and thevadjacent side wall Bor B The base portions of the vL -shaped members G tend to prevent leakage b'etweentltie piston mem ersand the piston chamber walls l3".

,Lealrage betweenthepiston wall 13 and the outer edge of each piston member is nnnn mined by the action of the spring on. the piston blade through the lug Eflsince this spring force tends to hold the bladeitselfm contact with the wall B In operation, centrifuiorce action on the piston bladeand on the U-shaped members H insures additional protection agamstleairage between the outer edge of each piston blade and the wall B \An advantage oftheparticular arrangement described is that centrifugal force tends to neutralize the tension oft is spring I and thus diminish the pressure inserted by theanemibers'G and H against ilhQSldQ and inner wall c1 the piston chamber as the engine speedincreases, thereby reducing friction at high speed when friction is of especial importance and when the tendency to leakage .past the pistons is of reduced importance.

To minimize leakage axially of each piston blade between working chambers at opposite sides of the piston, I have provided a pair of radially extending bar-like devices K received in radially extending slot-s formed in each side wall of each piston blade slot D and having pro ections K extending through apertures in side wall into the adjacent rotor cooling chamber space (1 or (F, into en-.

gagement with means tor pressing thememhers it: against the adjacent side of the corresponding piston blade E. As shown, the provisions for this purpose comprise a radially disposed helical spring Lasting on a toggle mechanism comprising a yoke member M and links N, the spring tending to move the yoke member M radially mward. Each. link member N is pivotally connected at one end to an equalizing structure connected tothe projections K of the two adjacent members K,-and is pivotally connected at its other end to one end of the yoke member M.-.

This equalizing structure comprises barlikejparts'iO and 05. There isza bar associated with each of the joint sealing members -K being secured to theprojections K of the :latter. Each linklmember N isconnected to member Dt, and'each spring L and yoke M.

is-located in the web port D each spring Lhas its outerend in engagement with a seat formed for the purpose on the a correspondingbar Oand the ends of the latter engage bearing seats 0 in the two bars" portions of the rotorstructurewhich form the outer walls of the corresponding pair oii tralize the action of the spring L and thus diminish the pressure exerted by the members K against the piston blade E as-the speediincreases hi h speed wheretriction is of especial importanceand when leakage through the slot D is 'ofreduced =importance.

To better dissipate heat absorbed 'from the working chambers by the rotor, the latter is tormed'with heat dissipating ribs D extending into the pockets or cooling spaces-d and d from the walls of the latter. When cooling of the stator due to heat r diation. to the atmosphere is insuflicient n'ieans may be provided for circulating a cooling fluid, usually" water, through cooling fluid passages formed in the stator structure. As s iown, this coolingfiuid is initially supplied to a chamber A in the base member A through a supply port A3 From the chamber A the liquid passes through a port or ports A into annular cooling fiuid spaces A formed one in each of the two parts of the housing body. The passages A cool the walls of the parts B andB as well as the piston chamber side and peripheral walls. The two passages A. connect at the top of the structure with a chamber A in a cooling fluid discharge connection A. 3

As shown in the" drawings, the effective area of each inlet port B may be varied by means of an ustable valve or throat memberP. The throat members P are mounted inguideways formed in the stator housing andlinclined tothe rot-oriplano of'revolution, and may beadjusted'by means of stems P the outer en'dsiot which project from the stator structure. The vexplosion engine forms a t This tends to "reduce friction at;

cooling spaces or pockets cl and d, and each and suitably located charge igniting devices Q.

\Vith the apparatus shown in the drawings, the space between the projecting ends of each adjacent pair of sliding piston members E at each side of the rotor constitutes a working chamber 6, the end walls of which are formed by said piston end portions, the side walls of which are formed by the correvendin side wall portion of the rotor body and the opposing portion of the adjacent piston chamber wall B or B and the inner and outer walls of which are formed by the corresponding portions of the piston chamber walls B and B In the intended operation of the particular form of apparatus shown in Figs. 1 to 5, an explosive mixture is drawn into each working chamber 6 as the latter moves past the corresponding inlet port 5 In pracmce suitable carburetor provisions are associated with each inlet port 13 but as provisions suitable for the purpose ar well known and their details form no part of the present invention they are not illustrated herein. As each working chamber Z) after receiving ts charge continues to advance, its volume 111- creases in consequence of the inclination of the adjacent portion of the correspondmg ton w Ll chamber B or B away from the rotor and each working chamber is enlarged to its maximum size at or very shortly after the time at which its rear wall, formed by the trailing piston E, passes beyond the front wall of the inlet port.

hereafter the working chamber 5 begins to diminish in volume thus compressing the charge. As shown in Fig. 2, the maximum compression in each working chamber occurs when, or immediatebefore, the movement of the rotor brings the front end of the working chamberopposite the charge igniting device Q. The ignition of the charge in each working chamber tends, o ircourse, to a great increase in pressure in the chamber, but the extent to which the pressure is thus increased is reduced in consequence of the expansion in the volume of the working chamber which begins to occur as soon as the piston E forming the front wall of the working chamber moves beyond the ignition device Q. As clearly appears from Fig. 2, each working chamber 6 is again expanded to its maximum capacity at or about the time when the piston E forming the front wall of the working chamber reaches the outlet port B The piston E forming the front wall of each working chamber 3) projects beyond the rotor a greater axial distance than does the piston forming the rear wall of the chamber during the period in which the working chamber volume is expanding after the charge is ignited, and the increase in working chamber pressure resulting from the ignition of the charge thus imparts energy to the rotor tending to main tain the latter in rotation.

In the construction shown in Figs. 1 to 5 there are eight Working chambers b at each side of the rotor and the operations occurring in each working chamber are repeated in each of tie other fifteen working chambers. With the parts proportioned and arranged as shown, during a single complete rotation of the rotor, each working chamber b is connected to the corresponding inlet port B during a little less than a quarter of the time required for the rotation; the charge in the working chamber is being compressed during another quarter; is being expanded during a third quarter of the time required for the rotation; and the working chamber is connected to the exhaust port during the remainder of the time required for the rotation. 'i'he described arrangement permits the working chambers to exhaust freely, and avoids objectionable wire drawing of the charges. tiince admitted to the working chambers the side walls of the rotor are substantially in contact with the convex portions of the piston chamber side walls B and B depressions, pockets or cavities d are advantageously formed in the rotor side walls, one for each working chamber to provide the latter with sufiicicnt volumetric capacity when the chamber is contracted to its minimum size. Each. pocket (5 is wedge-shaped with its blunt or deep end adjacent the forward end, having reference to the direction of rotary movement, of the working chamber to which it pertains. it will be understood, of 00 se, that doubling, trebling, or quadru- 1 lg the number of working chambers Z) and a corresponding increase in the number of inlet and exhaust ports 13 and B and ignition devices distributed about the rotor axis does not change the character or mode of operation of the apparatus other than by the multiplication of chambers and ports and the resultant increase in capacity of the engine. i

As shown, each piston chamber side wall B and B has each of its alternating convex and concave portions formed of two sections which are alternately inclined at a relativelv small angle to the plane of rotor rotation, and which are connected to one another by a portion parallel to said plane into which the inclined portions merge in a gradual manner. The formation of the piston chamber side walls l5 and B with alternating convex and concave portions shaped as shown, contributes to effective operation with a minimum of shock, friction, and wear. In consequence of the small diference in angle of inclination to the rotor rotation plane, of circumferentially adjacent sections of either side wall 13 or B the axial movements of each piston member E first in one direction and then in the other, are each initiated and terminated Lessors.

in a very-gradualmannera Theavoidance'of unduly rapid acceleration of each piston member E in any portion ofits toand fro movements, obviously contributes to minimize impact and excessive contactpressure between the ends of the piston and the side walls of the piston chamber, and thereby minim zes shock, frictional resistance, and resultant wear and vibration. It will be apparent also that the relatively slow axial acceleration ofthe pistons tends to prevent separation between their ends-and the adjacent walls of the stator and thusdirectly tend to prevent leakage the ends ofzthe pistons. v

By injecting-fuel into each working cham her 5 at the points at which thedevices Q are located, so that the injected fuel passes into a charge of air previously supplied to the chamber through the corresponding inlet port 13 and previously compressed in the chambert-o produce a temperature and pressurethereinat which the fuel injected will ignite, the apparatus shown in-Figs. 1' to 5 will operate'in a manner analogous to. that of an ordinary Diesel engine. For use of the form of apparatus shown'in Figs. 1 to 5 as-a Diesel'engine, thepockets or cavitiesd in the rotor may advantageously bemade shallower than are ordinarily'desirable in an explosive engine in which the fuel and air are premixed and are compresed in the working chambers preparatory to ignition.

The apparatus shown in Figs. 1 to 5 may be used as a gas compressor without significant change in form other than in the disposition of the inlet and outlet ports. For such use, as shown in Fig. 6, there maybe twoiexhaust ports X and-two inlet ports Y at each side of the rotor D, one exhaust port Xbeing located where the ignitiondevice-Qislocated in the construction first described, and the other being located-180 therefrom- An inlet port Y is located slightly in advance of each exhaust port. each inlet portadvantageously opening to the piston chamber along a circumferential extent thereof which corresponds to the major portion of the correponding section of the piston chamber side wall which is inclined away from the rotor plane. The rotor pockets orcavities d of'the construction first described, maybe omitted with-the arrangement shown in Fig. 6'when a high compression is desired, and when a 7 lower compression is desired, may be proport-ioned to the compression. required.

To adapt the form of apparatus shown in Figs. 1 to 5 for use as a turbine employing steam, compressed air,.or other compressed gas as the motive fluid, two inlet andtwo exhaust ports are provided at each side of the rotor, one exhaust port X being loatedsubstantially as in the construction shown in Figs. 1 to 5, and the other exhaust port being 180 therefrom as shown. in Fig. 7. Oneinletrport Y, is located substantially where-the ignition device Q is located in the constructionwfirst described, and the other inlet port at the same side of the turbine is located 180 therefrom. In general, in the use ofthe apparatus as a. turbine, .it is unnecessary to employ stator or rotor cooling provisions unless thecompresse-d air or gas forming the motivefluidlis supplied at high temperature.

To adapt apparatus of the form and character. shown inlfigs. 1, to ofor use as a liquid pump. two. inlet ports Yand two exhaust ports. X are providediat each side of the rotor as shownin Fig. 8. An inlet port Y opens to the piston chamber through each portion of the corresponding side wall of the piston chamber which is inclined away from the rotor plane of rotation, and an exhaust port X pens through each portion of the side wall which is inclined toward the plane of rotor rotation as is'shownin Fig. 8. In general, no stator cooling provisions are required in the use of the apparatusvas a liquid pump, and for such use the rotor pumps or cavities cZ may be eliminated.

It will'be understood of course, that in all forms of the invention, itli's essential in generalthat inlet'and outlet ports at one side of the apparatus be separated in acircumferential direction by adistance not less, and'usually slightly greater than the distance between an adiacentpair ofsliding pistons E.

While in accordance with the provisions of the 'statutes,I have illustrated and described the best formof embodiment of my invention nowknown to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departingfrom the spirit of my invention as set. forth in the appended claims;

andthat in some cases certain featuresof my invention maybe usedto advantage without a corresponding use of other features.

Having now described my invention what I claim as new and desire tosecure by Letters Patent, is

1. In arotary engine, a rotory comprisingan annular rotor body formed of two side partsand a central web part, said body being formed with slots to receive axially movable piston members, each of said side parts being chambered to form a cooling fluid space between each adjacent pair of said, slots. and being formed with a port through which said space opens to the atmosphere adjacent the axis of said body, and said central web, part being ported to connect, the side by side chambers in the two side members, ,and two sets of fan parts, one setat one side of the web part and tending to move air radially outward, and the other set at the other side of said web part and tending to move air, radially inward.

2. In arotary engine, a rotor formed with axially extendingpiston guideways and with cooling fluid passages communicating with said guideways at the inner edges of the latter, and means for passing a cooling fluid through said passages.

3. In a rotary engine comprising a rotor and a stator formed with an annular piston chamber coaxial with said rotor and into which the latter extends, the side walls of said piston chamber being circumferentially nndulatorv and said rotor being formed with axially extending piston guidewavs. piston members mounted in said guidewavs and extend ng between the side walls of said piston chamber and between the inner and outer walls thereof. and means for preventing leakage between said piston members and walls comprising; side bv side members mounted in each p ston member at each end the eof and each comprisinsr a rad allv extending portion and an ElYlflllV extendine' portion. the axiallv extending portion of one. engaging the inner wall of the piston chamber. and the ax allv extendinsportion of another of the members at one e d of each piston engaging the outer wall of the piston chamb r. and means located with n the piston for forcina bo h of the last mentioned. members ae'ainst the adiacent side p ton cham er side wall. and for forcinq sa d one member ra diallv inward against the inner wall of the piston chamber.

4. In a rotary engine compris ne; a rotor and a stator formed with an annular piston chamber co-axial with said rotor and into which the latter extends. the side walls of said piston chamber being circumferentiallv imdulatory and said rotor beino; formed with axially extendingpiston guidewavs. piston members mounted in said gruidewavs and extending between the side walls of said p ston chamber and between the inner and outer walls thereof. and means for preventing" leakage between said piston members and walls comprising side by side members mounted in each piston member at each end thereof and each comprising a radialh extending portion and an axially extendine portion. the ax all extending portion of one. engaging the inner wall of the piston chamber. and the axialli extendine' portion of another of the members at one end of each engaging; the outer wall of the piston chamber. and means located within the pi.- ton for forcing; both of the last mentioned members against the adjacent side piston chamber side wall. and for forcing" said one member radially inward against the inner wall of the piston chamber. said means coin-- prisinp. a resilient device the tension of which is aifected by a centrifugal force a d diminishes as the engine speed increa 5. In a rotary' engine. comprisinga 1501' and a stator formed with an annular piston chamber co-axial with said rotor and into which the latter extends, the side walls of said piston chamber being oircumferentially undulatory and said rotor being formed with axially extending piston p uideii'ays and piston members mounted in said gzuideways and extending between the side walls of said pi."- ton chamber and between the inner and outer walls thereof. and means for preventing leakage past said piston members comprising joint sealing members mounted in said rotor, and means also mounted. in said rotor for forcing said joint sealing members into a joint sealing position. said means including a resilient devic the tension of which is atfected by a centrifugal force action and diminishes as the engine speed increases.

6. In rotor engine comprising; a rotor. a stator formed with an annular piston chamr (Po-axial with said rotor and into which the latter extends. the said walls of said piston cham er bein i circumterentially undtilat v and. d rotor being formed with axially I idinoi piston gnideways and with radiallv extending; slots in the side walls of said iideways. piston members mounted in said gruidewa ws and extending; between the side walls of said piston chamber. and means iirei'entino' leakage between the piston mem bers and the walls of said ruideways com prising a joint sealing member mounted in each of said slots and means for yieldingljy pressing each of said joint sealingmembers into en'nQe-inent with the corre onding pis ton. and means compri a to irle connection between joint sealing members in adacent gznidewars d. springacting; on sad townie mechanism.

In a rotor engine comprising a rotor, a stator formed with an annular piston cham ber coaxial with. said rotor and into which the latter extends. the said walls of said piston chamber being circumferentiallv undu atory and said rotor being. formed with axialli' extending" piston guidewa is and with radiallv extendin slots in the side walls of said gruideways. iston members mounted in said en dei'rars and extending between the side walls of said piston chamber. and means for nrerentino; lealra 930 between the piston memhers and the walls of said nideways comprisinn; a ioint sealing: member mounted in each of said slots and means for yieldinsrh press-- ins: each of said ioint sealing me! aers into en 'anjemcnt with the corresponding piston. said means comprising a to 'rrle connection between joint sealing: members in adjacent iidew and a spring acting on said t mechanism subjected to a centrifugal force action diminishing the tension of said spring as the en gine speed increases.

8. in a rotary engine comprising a rotor d a stator formed with an annular piston 1 amber co-axial with said rotor and into which the latter extends. the side walls of said piston chamber being circumterentially undulatory and said rotor being formed with ibs axially extending piston guideways, piston members mounted in said guideways and ex tending between the side walls of said piston chamber and between the inner and outer walls thereof, and means for preventing leakage between said piston members and said walls comprising joint sealing members mounted in each piston member and means for subjecting said joint sealing members to an axial force and to a radial force comprising a toggle like structure mounted in each piston member and acting between joint sealing members at opposite ends thereof, and a radially disposed spring acting between said rotor and toggle structure.

9. In a rotary engine comprising a rotor and astator formed with an annular piston chamber coaxial with said rotor and into which the latter extends, the side walls of said piston chamber being circumferentially undulatory and said rotor being formed with axially extending piston guideways, piston members mounted in said guideways and extending between the side walls of said piston chamber and between the inner and outer walls thereof, and means for preventing leakage between said piston members and said walls comprising joint sealing members mounted in each piston member and means for subjecting said joint sealing members to an axial force and to a radial force comprising a toggle like structure mounted in each piston member and acting between joint sealing members atopposite ends thereof, and aradially disposed spring acting between said rotor and toggle structure and arranged to have its tension diminished by a centrifugal force action.

10. In a rotary engine comprising a rotor, a stator formed with an annular piston chamher coaxial with said rotor and into which the latter extends, the side walls of said piston chamber being circumferentially undulatory and said rotor being formed with axially extending piston guide-ways, piston members mounted in said guide-ways and extending between the side walls of said piston chamber, and means for preventing leakage between the piston chambers and the walls of said gui de-ways comprising joint sealing members and means for yieldingly pressing each of said joint sealing members into engagement with the COI'IGSPOHCliIlg piston, said means including a part subjected to centrifugal force action and tending to diminish the pressure of contact between said member and piston as the rotative speed of the rotor increases.

Signed at New York city, in the county of New York and State of New York, this 30th day of November, A. D. 1928.

LESLIE MILTON WOLF. 

